Liquid crystal displays have widely replaced the traditional CRT display devices because of its small volume, light weight, low power consumption, low voltage and no radiation and the like, and have been used in life and work.
A liquid crystal display is formed by aligning and assembling an array substrate and a color filter substrate, as shown in FIG. 1 and FIG. 2. FIG. 1 shows a plane structure of an array substrate in the prior art, and FIG. 2 is a cross-sectional diagram of the structure of the array substrate in FIG. 1 taken along line B-B′. As shown in FIG. 1 and FIG. 2, on a substrate 7, a gate metal layer (including a gate and gate line 8 in FIG. 1), a gate insulation layer 4, an active layer 5, a signal line metal layer, a pixel electrode layer, a passivation layer 2 and a common electrode layer are sequentially formed, wherein the signal line metal layer comprises a source and a drain of a thin film transistor, and data line 6 in the drawings, the pixel electrode layer comprises a pixel electrode 1 in FIG. 1, and the common electrode layer comprises a common electrode 3 in FIG. 2. Patterns of the active layer 5 and the signal line metal layer may be formed by using a half-tone mask process, as difference in difficulties in etching the active layer 5 and the signal line metal layer due to their difference in material, active tail phenomenon often occurs. For example, as shown in FIG. 2, active tail phenomenon occurs at edges of the active layer below the data line 6 in the display area (see the region A in FIG. 2). Usually, in order to avoid the occurrence of short circuit and signal interference, the pixel electrode 1 is required to be away from data line 6 as far as possible, however, as the existence of active tail (i.e., region A in FIG. 2), the existence of active tail must be taken into account during designing the distance between the pixel electrode 1 and the data line 6, which results in that the transmittance area of the pixel is decreased, and the aperture ratio is decreased.